use std::env;
use std::error::Error;
use std::fs;
pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents
        .lines()
        .filter(|line| line.contains(query))
        .collect()
}

pub fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    let query = query.to_lowercase();
    contents.lines()
        .filter(|line| line.to_lowercase().contains(&query))
        .collect()
}
pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.file_path)?;
    let results = if config.ignore_case {
        search_case_insensitive(&config.query, &contents)
    } else {
        search(&config.query, &contents)
    };
    for line in results {
        println!("{line}");
    }
    Ok(())
}
pub struct Config {
    query: String,
    file_path: String,
    ignore_case: bool,
}
impl Config {
    pub fn build(mut args: impl Iterator<Item = String>) -> Result<Config, &'static str> {
        args.next();
        Ok(Config {
            query: args.next().ok_or("Didn't get a query string")?,
            file_path: args.next().ok_or("Didn't get a file path")?,
            ignore_case: env::var("IGNORE_CASE").map_or(false, |var| var.eq("1")),
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn one_result() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.";

        assert_eq!(vec!["safe, fast, productive."], search(query, contents));
    }
    #[test]
    fn case_insensitive() {
        let query = "rUsT";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Trust me.";

        assert_eq!(
            vec!["Rust:", "Trust me."],
            search_case_insensitive(query, contents)
        );
    }
}
